Section 3: Consider the Diagnosis of Valley Fever



Spectrum of clinical manifestations for Valley Fever

The incubation period of coccidioidal infection ranges from seven to 21 days after which a variety of manifestations develop. The most common symptoms are fatigue, night sweats, and pulmonary symptoms (cough, chest pain, dyspnea, and hemoptysis). Although difficult to quantify, fatigue is often a prominent symptom. Stories like "I went to bed and didn't wake up for 15 hours" or "I got up had breakfast and then was exhausted" are common. When a cough is present it frequently is not particularly productive of large amounts of sputum. Fever is present in 46% of patients. A headache is present in approximately one-fifth of the patients with early infection; fortunately, as a transient symptom, this does not always represent meningitis. Weight loss is also a sign associated with coccidioidal infections. It is apparent from this that the clinical presentation overlaps substantially with the presentation of many other types of respiratory illnesses.

Skin manifestations include a diffuse nonpruritic maculopapular eruption which may occur in 16% of males and 7% of females, especially children and young adults. It is so transient and seemingly inconsequential that it is often missed. More notable are Erythema nodosum (3% of males, 23% of females) and Erythema multiforme. These two rashes can be caused by a long list of stimuli in addition to coccidioidomycosis. However, when found in patients from within the endemic area of C. immitis, Valley Fever should be strongly suspected. Another symptom is diffuse and migratory arthralgia (22% of patients). Joints may be mildly inflamed and painful but do not exhibit an effusion. The triad of fever, E. nodosum, and diffuse arthralgias has produced the synonym of "desert rheumatism" for the disease. All of these manifestations are thought to be immunologically mediated and not the consequence of viable fungal cells in either the skin or the joints.

Chest radiographs often, but not always, disclose abnormalities associated with the early infection. Pulmonary infiltrates are usually one- sided and are typically patchy and not as consolidated as seen with bacterial infections. Often there is associated ipsilateral hilar adenopathy. Peripneumonic pleural effusions may also occur as part of a primary infection. Although disease of one lung is the rule, the process can occasionally be bilateral. Examples of these abnor-malities are shown in the accompanying figures.



Clinical Manifestations of VF

Symptoms

Fatigue

Night sweats

Cough

Chest pain

Dyspnea

Hemoptysis

Headache

Arthralgias

Signs

Fever

Weight loss

Erythema nodosum

Erythema multiforme

Chest radiographs

Pulmonary infiltrates

Hilar adenopathy

Pleural effusions



Table 2: Clinical manifestations of Valley Fever

Routine laboratory findings commonly show nonspecific abnormalities. Peripheral blood leukocyte counts are often normal although eosinophilia is frequently increased, sometimes to strikingly high levels. Erythrocyte sedimentation rates are often elevated.

Attempts to use clinical presentation and routine laboratory results as an indicator of coccidioidal infection have not been very satisfying. In one study, several patient findings were significantly associated with coccidioidal infection as compared to patients with other causes of acute respiratory problems. However, the predictive value of these abnormalities was very limited and not of practical help in identifying most infections.



Selecting patients for evaluation

Since the signs, symptoms and routine laboratory abnormalities are nonspecific, virtually any patient evaluated for a variety of complaints, especially those related to the respiratory system, could arguably be evaluated for coccidioidomycosis. The more patients that are tested for Valley Fever, the more infections are likely to be found. On the other hand, despite the prevalence of Valley Fever within the endemic patient population, many other acute illnesses also exist. Thus, by increasing provider sensitivity and the number of tests ordered to diagnosis Valley Fever, the overall proportion of tests that are diagnostic will decrease.

A critical step for clinicians in a busy practice is to establish routine indications for ordering the appropriate tests. In the table, several indications are proposed which are selected for simplicity and application to common situations.

 

 

 

 

 

 

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